Pinitol and chiro-inositol exert insulin-like effect by mediating post-receptor signaling pathway. Total chiro-inositol concentrations, including pinitol, chiro-inositol, and their derivatives, were determined in 115 natural and food materials to identify economical sources for mass production of pinitol. Carob pod, Bougainvillea, soy whey, and soybean oligosaccharides were rich sources of chiro-inositol. Pinitol was isolated from soy whey and carob pod, considered as economically viable sources, by chromatographic separation using activated carbon. Soy and carob pinitols had same chemical structure as that of reference pinitol based on HPLC and NMR results. Oral administration of soy pinitol and carob pinitol (10 mg/kg) significantly decreased blood glucose at 2-6 hr in streptozotocin-induced diabetic rats. These results suggest pinitol isolated from soy whey and carob pod could be beneficial in controlling blood glucose in animal model of diabetes mellitus.